1. Field of the Invention
The present invention relates to hay balers. More particularly, the present invention relates to a retrofittable measuring device to determine bale size for use in hay balers.
2. Description of the Prior Art
Hay balers are complicated mechanical devices designed to pick up previously cut hay in the field, form it into uniform bales, tie the bales, and drop the bales on the ground as the operator drives the hay baler at a reasonably uniform rate of speed. Modern hay balers are extremely complicated, requiring constant maintenance and adjustment to operate properly. One area which becomes uncalibrated particularly quickly are the mechanisms for measuring and forming uniform bales of hay.
A detailed description of the structure and operation of hay balers may be found in many sources. For example, refer to John Deere Operator Manual OME81606 (BALER 468), or AGCO Hesston Form Number 700 710 200 (4655 Square Baler). However, a brief discussion of the measuring and tying mechanisms on conventional hay balers will assist in understanding the current invention. FIG. 1 shows a string box 10 containing several balls 12 of string 15. The particular string box 10 shown in FIG. 1 contains six balls of string. The end of one ball of string is tied to the beginning of the next roll until three rolls are tied together, and the beginning of the first roll is threaded through several eyelet's 13 and a hole 14 before being provided to one of the two tying mechanisms. The other three rolls are similarly tied together, strung through separate eyelet's 13 and the other hole 14, and provided to the other tying mechanism.
FIGS. 2 and 3 show the measuring mechanism used in conventional hay balers. All conventional hay balers use approximately the same measuring mechanism, with some small changes. Measuring assembly 35 comprises trip arm 34, arms 36 and 38, arc 37, and stop collar 42. Star wheel 44 is connected to metering gear 45 via rod 46. Trip arm 34 moves into and out of contact with cam 22.
The measuring mechanism starts out in the configuration shown in FIG. 2, as the hay bale is being formed. Star wheel 44 contacts the top surface of the hay bale being formed. As the hay moves past, star wheel 44 turns counterclockwise, turning rod or shaft 46 connected to metering gear 45. Metering gear 45 causes arc 37 to move upward until the shaft moves into trip notch 40. This allows the measuring assembly 35 to move left and rotate clockwise slightly, except trip arm 34, which rotates counterclockwise, so that end 32 moves out of contact with dog 31, and reset roller 33 moves out of the way of protrusion 29. Spring loaded gear 20 begins to rotate counterclockwise. This is the configuration shown in FIG. 3
Gear 20 rotates counterclockwise one revolution. As it rotates, lower portion 23 of reset cam 22 forces reset roller 33 to the right, rotating trip arm 34 clockwise. This causes the measuring assembly to rotate clockwise back to its original position shown in FIG. 2. Metering gear 45 stops when it hits stop collar 42. Protrusion 29 on rim 28 moves roller 33 slightly upward, moving end 32 of arm 34 back into position to contact dog 31 and prevent gear 20 from rotating further.
Chain 26 engages with gear teeth 24, and is used to drive the knotting mechanism shown in FIGS. 4A-4F. In some hay balers, chain 26 is replaced by a gear for driving the knotting mechanism. The size of the hay bales is controlled by loosening stop adjustment 43, moving stop collar 42, and retightening stop adjustment 43. This method of determining hay bale size is inherently imprecise, and stop collar 42 is subject to jarring and vibrations which cause it to move while the baler is operating. Thus, hay bales from a short period of baling can vary in size so much they are difficult to stack.
FIGS. 4A through 4F show the bale tying process mechanically triggered by the rotation of gear 20. In FIG. 4A, the bale is being formed, and string 15 is held in string disk 49 by string holder 48. It is fed from string box 10. String 15 feeds down from string holder 49, over billhook 52, through guide 51, over the top of bale. Needle 60 holds the other end of string 15, pulling it around under the bale. In FIG. 4B, needle 60 brings the end of string 15 up through guide 51 and into string disk 49. In FIG. 4C, billhook 52 starts to rotate to the left, forming a loop of string around the hook. In FIG. 4D, billhook jaw 54 opens to receive the string as billhook 52 continues to rotate. In FIG. 4E, billhook jaw 54 closes to pull the knot tight, and knife 56 on knife arm 57 cuts the string. Needle 60 withdraws, pulling string 15 in place for the next bale. In FIG. 4F the severed ends of the string slide out of billhook 52.
A need remains in the art for improved retrofittable apparatus for measuring hay bales in hay balers.